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Novel Enantioselective Synthesis of Functionalized Pyridylarsanes by a Chiral Palladium Template Promoted Asymmetric Hydroarsanation Reaction
Author(s) -
Liu Fengli,
Pullarkat Sumod A.,
Li Yongxin,
Chen Shuli,
Leung PakHing
Publication year - 2009
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200900460
Subject(s) - chemistry , organopalladium , naphthylamine , palladium , enantioselective synthesis , denticity , chelation , chiral auxiliary , medicinal chemistry , absolute configuration , stereochemistry , organic chemistry , catalysis , crystal structure
The asymmetric hydroarsanation reactions between diphenylarsane and ( E )‐1‐phenyl‐3‐(pyridin‐2‐yl)‐2‐propenone and ( E )‐1‐methyl‐3‐(pyridin‐2‐yl)‐2‐propenoate have been achieved by use of the organopalladium complex containing ortho ‐metalated ( R )‐[1‐(dimethylamino)ethyl]naphthalene as the chiral reaction template in high regio‐ and stereoselectivities under mild conditions. Hydroarsanation of ( E )‐1‐phenyl‐3‐(pyridin‐2‐yl)‐2‐propenone with diphenylarsane generated two stereoisomeric products in the ratio of 3:1 as five‐membered As–N bidentate chelates on the chiral naphthylamine palladium template. Using the same chiral metal template, the corresponding hydroarsanation reaction with ( E )‐1‐methyl‐3‐(pyridin‐2‐yl)‐2‐propenoate gave only one product as a six‐membered As–N bidentate chelate. The naphthylamine auxiliary could be removed chemoselectively by treatment with concentrated hydrochloric acid to form the corresponding optically pure neutral complexes. Subsequent ligands displacement from the palladium using aqueous potassium cyanide generated the optically pure keto‐ and ester‐functionalized chiral pyridylarsane ligands. The absolute configuration and the coordination properties of the pyridylarsanes have been established by single‐crystal X‐ray analysis.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)